Tissue may be destroyed, ablated, or otherwise treated using thermal energy during various therapeutic procedures. Many forms of thermal energy may be imparted to tissue, such as radio frequency electrical energy, microwave electromagnetic energy, laser energy, acoustic energy, or thermal conduction. In particular, radio frequency ablation (RFA) may be used to treat patients with tissue anomalies, such as liver anomalies and many primary cancers, such as cancers of the stomach, bowel, pancreas, kidney and lung. RFA treatment involves destroying undesirable cells by generating heat through agitation caused by the application of alternating electrical current (radio frequency energy) through the tissue.
Various RF ablation devices have been suggested for this purpose. For example, U.S. Pat. No. 5,855,576 describes an ablation apparatus that includes a plurality of electrode tines deployable from a cannula. Each of the tines includes a proximal end that is coupled to a generator, and a distal end that may project from a distal end of the cannula. The tines are arranged in an array with the distal ends located generally radially and uniformly spaced apart from the distal end of the cannula. The tines may be energized in a bipolar mode (i.e., current flows between closely spaced electrode tines) or a monopolar mode (i.e., current flows between one or more electrode tines and a larger, remotely located common electrode) to heat and necrose tissue within a precisely defined volumetric region of target tissue. To assure that the target tissue is adequately treated and/or to limit damaging adjacent healthy tissues, the array of tines may be arranged uniformly, e.g., substantially evenly and symmetrically spaced-apart so that heat is generated uniformly within the desired target tissue volume.
When using the above described devices in percutaneous interventions, the cannula is generally inserted through a patient's skin, and the tines are deployed out of the distal end of the cannula to penetrate target tissue. The tines are then energized to ablate the target tissue. Such procedure results in surgical wounds that are much smaller in size than those associated with open surgical settings, and therefore, improves healing time for the patient. However, the size of a surgical wound is still affected by the overall cross sectional dimension of the ablation device—i.e., the larger the ablation device used, the larger the wound size.
The above described devices are generally constructed by manufacturing the tines in individual pieces, and welding or soldering the tines onto a shaft. Such manufacturing technique is time consuming, and increases the risk of manufacturing error. Also, the connection adhering the individual tines to the shaft increases the overall cross sectional dimension of the ablation device, which in turn, increases the size of surgical wounds when the ablation device is used to treat patients.
Thus, there remains a need to provide for improved methods of manufacturing ablation devices.